mod 3

• ecosystem


  a combination of all the organisms (biotic factor) living in a community and all the non-living features (abiotic factor) with which they interact with
• community


  a group of different species living together and interacting with one another in a particular habitat
• organism habitat


  where it lives at a particular time
• The Theory of Natural Selection

  In any population, there are variations between the individuals. More offspring are produced than are needed and there is a constant struggle for survival

  Those individuals with favourable characteristics (adaptations) are selected by the environment to survive and reproduce. Those without favourable characteristics are removed from the population.

  The individuals with favourable characteristics reproduce and pass on these favourable characteristics to their offspring.

  Over time these favourable characteristics become more common in the population
• selection pressures


  factors that affect the survival of an individual within a population, therefore driving natural selection. can also affect the distribution and abundance
• distribution


  where a species is found in an ecosystem
• abundance


  how many individuals of that species live throughout the ecosystem
• biotic factors

  seasonal availability and abundance of food

  the number of competitors

  the number of mates available

  the number of predators

  the number and variety of disease causing organism
• abiotic factors


  temperature, soil type , exposure to natural forces (waves, tides, winds)

  light availability

  water

  availability of gases (oxygen and carbon dioxide)
• ecology


  study of interrelationships between different types of organism and their environment
• autotroph


  an organism that produces its own nutrients through either photosynthesis(a plant) or chemosynthesis(bacteria)
• heterotroph


  an organism that cannot produce its own food and has to eat another organism for food
• producer


  an autotroph
• consumer 


  heterographic organism that consumes others
• carnivore


  an organism that eats meat
• herbivore


  an organism that eats plants
• omnivore


  an organism that eats plants and meats
• scavenger


  an animal that feeds on dead organisms
• decomposer


  an organism that breaks down dead plants and animals and returns the nutrients to the soil to be reused by producers
• food chains


  sequences of organisms from producers to consumers along which energy flows in an ecosystem. Energy cannot be created or destroyed but is changed from one form to another
• food webs


  shows a number of interacting food chains in an ecosystem. Food webs always start with producers at the bottom of the page and show the trophic levels above
• predator-prey relationship

  predator consumes the prey. Over time in a community, the number of prey with always peak before the number of predators
• competition


  the struggle between organisms for the same resource. Usually for a resource that is limited in supply but valuable to survival
• allelopathy


  occurs when an organism produces a substance which prevents the abundance of another organism from a different species
• symbiosis


  the type of interaction between organism where two different species live together in close association
• mutualism (symbiosis)


  both organisms benefit and neither could survive without each other
• commensalism (symbiosis)


  a relationship in which one organism benefits and the other one is not harmed
• parasitism (symbiosis)


  a relationship where one organism feeds on a host, the parasite will benefit while the host is harmed
• niche


  part of an ecosystem that an organism occupies. Refers to all the resources that a species uses, both biotic and abiotic factors. No two species will ever occupy the same niche
• adaptation


  feature of an organism that makes it well suited to its environment and lifestyle. Help the organism to survive and reproduce in an ecosystem and are inherited from one generation to another via the DNA
• structural adaptation


  shape and size of an organism and its various body parts
• physiological adaptation


  relating to the way the organism functions, how its body works
• behavioural adaptation


  how an organism responds to its environment
• ecosystem


  a combination of all living (biotic factors) living in a community and all non-living features (abiotic factors) with which they interact with
• environment


  made up of non-living components (abiotic factors)
• community


  a group of different species living together and interacting with one another in a particular habitat.
• organisms habitat


  where an organism lives at a particular time
• organism ecosystem


  provides it with nutrients, water, shelter and an opportunity to mate
• selection pressures are factors often in the environment, that affect the survival of an individual within a population, therefore driving natural selection.
• distribution


  where a species is found in an ecosystem